1. Field of the Invention
The present invention relates to a reaction furnace and a method of operating the same and, more particularly, relates to a suitable reaction furnace for use in a manufacturing process of a semiconductor device and a method operating the same.
2. Description of the Prior Art
An oxidation diffusion furnace is used in general as a reaction furnace. (For example, Collection of New Technique of ULSI Factory-New Process and Automation, pp. 118-123, Realize Co., Japan, 1986; Automation of LSI Factory-Collection of New Process Technique, pp. 176-184, Realize Co., Japan, 1984; Electronic Material in Separate Volume-Guide Book for ULSI Manufacture/Testing Device, pp. 54-56, pp. 79-83, Japan, 1986).
Conventionally, such type of reaction furnace is structured as shown in FIG. 1. An outline of such reaction furnace will be described with reference to FIG. 1. Referring to FIG. 1, a container 1 has a horizontal type of treatment chamber 4 capable of housing a boat 3 holding a member 2 to be treated such as a semiconductor wafer. A gas inlet 5 and a vacuum outlet 6 are connected to the container 1. In the thus structured reaction furnace, the treatment chamber 4 housing the boat 3 holding the member 2 to be treated is evacuated. By letting various kinds of gas be introduced in this chamber from the inlet 5, a thin film can be formed on the surface of the heated member 2 to be treated.
In addition, there are some methods of heating the member 2 to be treated, that is, by means of a resistance wire, infrared lamp, or high frequency.
A reaction furnace of a type shown in FIG. 2 is also employed in the prior art, wherein a container 7 comprises a treatment chamber 10 having two electrodes 8 and 9 at upper and lower portions thereof. The electrodes 8 and 9 are arranged in the container 7. A member 11 to be treated such as a semiconductor wafer is positioned on the lower electrode 9. Also, a gas inlet 12 and vacuum outlets 13 are connected to said container 7.
In the thus structured reaction furnace, the treatment chamber 10 is evacuated, with the member 11 to be treated placed on the lower electrode 9 in the container 7. By letting various kinds of gas be introduced in this chamber from the gas inlet 12 and applying a direct current high voltage between both electrodes 8 and 9, a thin film can be formed on the surface of the member 11 to be treated.
With the above conventional reaction furnaces, it is necessary to take in and out the members 2 and 11 to be treated between the atmosphere and the treatment chamber 4 and 10 during the treatment. At that time, the temperature is very high in the treatment chamber 4 and 10. Therefore, the members 2 and 11 to be treated are heated before the treatment starts and they react with the air in the treatment chambers 4 and 10. Also, the air comes in contact with the heated members 2 and 11 to be treated after the treatment. Thus, an undesirable film was formed on the members 2 and 11 to be treated, whereby problems were caused that it was difficult to control a film thickness and this film with a uniform thickness can not be formed.